As a result of intensive research on biodiversity and ecosystem functioning over the last two decades, community structure is now well recognized as a primary determinant of ecosystem functioning. Nevertheless, explaining how community structure affects ecosystem functioning remains challenging because their relationships often appear idiosyncratic and difficult to predict. As a key to understanding these apparent idiosyncrasies, we are investigating how immigration history may affect ecosystem functioning via its effect on community structure.
Using wood-decaying fungi, we have recently found that large differences in ecosystem functioning can be caused by subtle differences in immigration history. In both laboratory and field experiments, direct manipulation of early immigration history resulted in substantial differences in fungal species richness and composition and, as a consequence, differences of an equal or larger magnitude in the rate of decomposition and carbon release from wood. These effects were significant across a range of nitrogen availabilities observed in forests. Our findings highlight the importance of considering immigration history in explaining the relationship between biodiversity and ecosystem functioning.
As a driver of both the structure and function of communities, immigration history may be a conceptually unifying process that explains both systematically. We are investigating this possibility further using nectar-inhabiting microbes.